U.S. patent number 10,875,033 [Application Number 16/208,635] was granted by the patent office on 2020-12-29 for removal of ferromagnetic material from a fluid stream.
This patent grant is currently assigned to CONOCOPHILLIPS COMPANY. The grantee listed for this patent is ConocoPhillips Company. Invention is credited to Samer Adham, Eman Alshamari, Dareen Zuhir Omar Dardor, Altaf Hussain, Arnold Janson, Joel Minier-Matar, Nabin Upadhyay.
![](/patent/grant/10875033/US10875033-20201229-D00000.png)
![](/patent/grant/10875033/US10875033-20201229-D00001.png)
![](/patent/grant/10875033/US10875033-20201229-D00002.png)
![](/patent/grant/10875033/US10875033-20201229-D00003.png)
![](/patent/grant/10875033/US10875033-20201229-D00004.png)
![](/patent/grant/10875033/US10875033-20201229-D00005.png)
United States Patent |
10,875,033 |
Janson , et al. |
December 29, 2020 |
Removal of ferromagnetic material from a fluid stream
Abstract
A magnetic filter assembly 1 is described which is suitable for
incorporating into a fluid system such that a process fluid flows
through the filter to remove ferromagnetic particles in the fluid.
The filter assembly 1 comprises a housing 2 having a flow chamber.
The housing also comprises one or more elongate hollow sleeves 10
extending into the flow chamber such that, in use, an exterior
surface of each sleeve 10 is exposed to the process flow and an
interior surface of each sleeve 10 is sealed from the process flow.
Each sleeve 10 has an opening via which the interior surface of the
sleeve is open or openable to the environment whilst remaining
sealed from the process flow. Each sleeve has received in it a
magnet 12, the magnet being removable from the sleeve via the
opening. In this way, cleaning of the filter by removal of the
magnets is facilitated, without exposing the process flow.
Inventors: |
Janson; Arnold (Doha,
QA), Adham; Samer (Doha, QA), Minier-Matar;
Joel (Doha, QA), Hussain; Altaf (Doha,
QA), Alshamari; Eman (Doha, QA), Upadhyay;
Nabin (Doha, QA), Dardor; Dareen Zuhir Omar
(Doha, QA) |
Applicant: |
Name |
City |
State |
Country |
Type |
ConocoPhillips Company |
Houston |
TX |
US |
|
|
Assignee: |
CONOCOPHILLIPS COMPANY
(Houston, TX)
|
Family
ID: |
1000005267309 |
Appl.
No.: |
16/208,635 |
Filed: |
December 4, 2018 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20190176164 A1 |
Jun 13, 2019 |
|
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
62595784 |
Dec 7, 2017 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B03C
1/0332 (20130101); B03C 1/284 (20130101); B03C
1/288 (20130101); B03C 1/286 (20130101); B03C
2201/28 (20130101); B03C 2201/18 (20130101) |
Current International
Class: |
B03C
1/033 (20060101); B03C 1/28 (20060101) |
Field of
Search: |
;210/695,222 ;96/1
;209/223.1,214,224 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Norris; Claire A
Attorney, Agent or Firm: Conocophillips Company
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a non-provisional application which claims
benefit under 35 USC .sctn. 119(e) to U.S. Provisional Application
Ser. No. 62/595,784 filed Dec. 7, 2017, entitled "REMOVAL OF
FERROMAGNETIC MATERIAL FROM A FLUID STREAM," which is incorporated
herein in its entirety.
Claims
The invention claimed is:
1. A method of filtering ferromagnetic material from a process
fluid, the method comprising: a. providing a process fluid circuit,
the circuit incorporating a magnetic filter assembly; b. the
magnetic filter assembly comprising: i. a filter housing having a
flow chamber which, in use, is exposed to the process fluid; ii.
the filter housing comprising one or more elongate hollow sleeves
extending into the flow chamber such that, in use, an exterior
surface of each sleeve is exposed to the process fluid and an
interior surface of each sleeve is sealed from the process fluid;
wherein iii. each sleeve has an opening at a proximal end thereof
via which the interior surface of each sleeve is open or openable
to the environment whilst remaining sealed from the process fluid;
iv. each sleeve has received in it a magnet, the magnet being
removable from the sleeve via the opening; c. causing the process
fluid to flow through the filter assembly; d. periodically cleaning
the filter assembly by removing the magnets from the sleeves
without exposing the interior of the process fluid circuit to the
surroundings; e. after the magnets have been removed, flushing
cleaning liquid through the filter assembly to remove accumulated
ferromagnetic material; f. temporarily suspending influent flow of
cleaning liquid; sparging gas through the filter assembly to create
turbulence and thereby aid in the removal of accumulated
ferromagnetic material.
2. A method as claimed in claim 1, wherein the sparging gas is
nitrogen gas.
3. A method as claimed in claim 1 further comprising injecting a
chemical into the process fluid circuit upstream of the filter
assembly which chemical reacts with one or more dissolved
contaminant compounds in the process fluid to produce one or more
ferromagnetic precipitates.
4. A method as claimed in claim 3 wherein the injected chemical is
hydrogen peroxide and the process further comprises heating the
process fluid upstream of the filter assembly.
5. A method as claimed in claim 1 wherein the filter assembly is
connected into a side stream of a main process fluid circuit.
6. A method of filtering ferromagnetic material from a process
fluid, the method comprising: a. providing a process fluid circuit,
the circuit incorporating a magnetic filter assembly; b. the
magnetic filter assembly comprising: i. a filter housing having a
flow chamber which, in use, is exposed to the process fluid; ii.
the filter housing comprising one or more elongate hollow sleeves
extending into the flow chamber such that, in use, an exterior
surface of each sleeve is exposed to the process fluid and an
interior surface of each sleeve is sealed from the process fluid;
wherein iii. each sleeve has an opening at a proximal end thereof
via which the interior surface of each sleeve is open or openable
to the environment whilst remaining sealed from the process fluid;
iv. each sleeve has received in it an electromagnet; c. causing the
process fluid to flow through the filter assembly; d. periodically
cleaning the filter assembly by deactivating the electromagnets
without exposing the interior of the process fluid circuit to the
surroundings; f. after the magnets have been deactivated, flushing
cleaning liquid through the filter assembly to remove accumulated
ferromagnetic material; g. temporarily suspending influent flow of
cleaning liquid; sparging gas through the filter assembly to create
turbulence and thereby aid in the removal of accumulated
ferromagnetic material.
7. A method as claimed in claim 6, wherein the sparging gas is
nitrogen gas.
8. A method as claimed in claim 6 further comprising injecting a
chemical into the process fluid circuit upstream of the filter
assembly which chemical reacts with one or more dissolved
contaminant compounds in the process fluid to produce one or more
ferromagnetic precipitates.
9. A method as claimed in claim 8 wherein the injected chemical is
hydrogen peroxide and the process further comprises heating the
process fluid upstream of the filter assembly.
10. A method as claimed in claim 6 wherein the filter assembly is
connected into a side stream of a main process fluid circuit.
Description
FIELD OF THE INVENTION
This invention relates to processes and apparatus for removing
ferromagnetic material from a fluid stream.
BACKGROUND OF THE INVENTION
It is possible for fluid streams of many kinds to become
contaminated with ferromagnetic material such particles of iron or
iron oxides. It is sometimes possible to remove this material by
means of an applied magnetic field. Apparatus for this purpose is
known, for example, in the food industry and in the automotive
industry. Commonly, particles of iron or iron oxide from pipework
may become entrained in a fluid flow passing through the pipework.
A substantial proportion of this type of ferromagnetic material may
be separated from the fluid steam by a permanent magnet or an
electromagnet suitably positioned with respect to the pipework.
Normally a cleaning or flushing operation is required periodically
to remove accumulated ferromagnetic material.
Previous solutions have tended to suffer from one or more issues
which make them unsuitable for certain high flow applications, for
example as encountered in the oil and gas industry. For example,
many prior solutions involve having the magnetic component directly
exposed to the fluid which can mean that removing accumulated
ferromagnetic material is difficult. This can make cleaning complex
and potentially inadequate. Mechanical wipers or scrapers are
sometimes used, but this adds cost and complexity and the cleaning
is not always adequate. Furthermore, in these types of filters the
fluid to be treated, or at least the interior of the pipework or
other apparatus through which it normally flows, needs to be
exposed in order to clean the device; this may be hazardous to
personnel or may result in contamination of the fluid or
pipework.
Other solutions involve having the magnetic component arranged on
the outside of pipework or on the outside of a filter housing
enclosing the flow. This may address the problem of removal of
accumulated ferromagnetic particles since the magnetic field can be
removed or switched off. However, in this arrangement the magnetic
field may be applied inefficiently to the flow, with much or even
the majority of the field extending away from pipeline and not
interacting with the fluid flow to be treated. This is not only
inefficient, therefore requiring large magnets, but may also be a
hazard to personnel or other equipment, e.g. electronic equipment,
in the vicinity. Shielding may be required, with associated cost
and bulk. Solutions of this type tend to be heavy and bulky.
Even with the possibility of the magnetic field being disabled in
some way, e.g. by removal of a permanent magnet or switching off an
electromagnet, magnetic particles may remain adhered to a surface
which has been directly exposed to the process fluid and upon which
they have accumulated due to an applied magnetic field. Desirably,
some additional method of cleaning this surface would be provided
without opening the process fluid or interior of the pipework or
other apparatus to the environment.
Some known filters have a magnet external to a filter housing and
temporarily magnetizable elements made e.g. from soft iron located
within the housing. This has the advantage of having a magnetized
element in direct contact with the fluid which can provide for a
strong field/fluid interaction, but has the problem that such
elements can become permanently magnetized to a degree which can
make cleaning difficult even when the external magnet is removed or
switched off.
U.S. Pat. No. 8,900,449 discusses a magnetic filter comprising a
filter housing installed in pipework. The housing has a cover which
may be opened thereby exposing the interior of the filter and
pipework to the environment. After opening the cover, a number of
rod-shaped magnetic elements may be removed from sleeves which
extend into a filter chamber. The sleeves may also be removed, or
the entire assembly of magnetic rods and sleeves together with a
supporting frame.
GB762,163 describes a magnetic filter comprising an annular filter
housing having corrugated soft iron pole pieces within its annular
flow path. External to the housing and located in the center of the
annulus is a permanent magnet whose magnetic field is channeled by
the pole pieces so that flow is exposed directly to magnetized
components. When cleaning is required, the permanent magnet is
withdrawn. In addition, the flow of process fluid is stopped and a
flushing operation performed using a separate inlet and outlet.
BRIEF SUMMARY OF THE DISCLOSURE
The invention more particularly includes a magnetic filter assembly
suitable for incorporating into a fluid system such that a process
fluid flows through the magnetic filter, the filter assembly
comprising: a filter housing having a flow chamber which, in use,
is exposed to the process fluid; the filter housing comprising one
or more elongate hollow sleeves extending into the flow chamber
such that, in use, an exterior surface of each sleeve is exposed to
the process flow and an interior surface of each sleeve is sealed
from the process flow; wherein each sleeve has an opening at a
proximal end thereof via which the interior surface of each sleeve
is open or openable to the environment whilst remaining sealed from
the process flow; each sleeve has received in it a magnet, the
magnet being removable from the sleeve via the opening.
The invention also includes a method of filtering ferromagnetic
material from a process fluid, the method comprising: connecting a
filter assembly as described above to a process fluid circuit and
causing the process fluid to flow through the filter assembly; and
periodically cleaning the filter assembly by removing the magnets
from the sleeves without exposing the interior of the process fluid
circuit to the surroundings.
The invention also includes a method of filtering ferromagnetic
material from a process fluid, the method comprising: connecting a
filter assembly as described above to a process fluid circuit and
causing the process fluid to flow through the filter assembly; and
periodically cleaning the filter assembly by deactivating the
electromagnets without exposing the interior of the process fluid
circuit to the surroundings, and optionally also removing the
electromagnets.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete understanding of the present invention and benefits
thereof may be acquired by referring to the following description
taken in conjunction with the accompanying drawings in which:
FIG. 1A is a schematic elevation of a filter unit according to the
invention;
FIG. 1B is a schematic plan view from above of a filter unit
according to the invention;
FIG. 2A is a schematic elevation of a sleeve insert assembly of a
filter unit according to the invention;
FIG. 2B is a schematic plan view of a sleeve insert assembly of a
filter unit according to the invention;
FIG. 3 is a schematic view of alternative magnetic rod elements
from a filter unit according to the invention;
FIG. 4A is a sectional view taken on the line A-A in FIG. 1B;
FIG. 4B is a sectional view taken on the line B-B in FIG. 1A;
FIG. 5A is a sectional view, similar to FIG. 4A, of a second
embodiment of the invention which incorporates aerators; and
FIG. 5B is a sectional view, similar to FIG. 4B, of a second
embodiment of the invention which incorporates aerators.
DETAILED DESCRIPTION
Turning now to the detailed description of the preferred
arrangement or arrangements of the present invention, it should be
understood that the inventive features and concepts may be
manifested in other arrangements and that the scope of the
invention is not limited to the embodiments described or
illustrated. The scope of the invention is intended only to be
limited by the scope of the claims that follow.
Referring firstly to FIG. 1A, a magnetic filter 1 comprises a
filter housing 2 of generally cylindrical shape. The cylinder is
arranged with its axis vertical. At the bottom is an end cap 15
through which is a conduit which connects via respective valves to
a feed inlet 3 and a drain 6.
In the sides of the cylinder 2 at its upper end are a product
outlet 4 (for filtered process fluid) and a backwash inlet 5, both
with respective valves. The top of the cylinder is sealed with a
top plate 9 (or "tubesheet"). Sleeves of thin plastics material
pass through and are sealed around apertures in the top plate 9;
the sleeves extending down into the filter chamber defined within
the housing 2, almost for the full length of the housing 2.
In the plan view FIG. 1B, the top plate 9 and seven sleeves 10 can
be seen. Received within each sleeve is a magnet rod 12 comprised
of a strong permanent magnet made for example of an alloy of
neodymium, iron and boron (though any suitable material may be
used). Each magnet rod 12 has a handle 7 at the top which can be
used to withdraw the rods individually.
The top plate 9 may be separated from the cylinder by means of
releasable fastenings (not shown) and replaced again, re-making the
seal. As seen in FIGS. 2A and 2B, the sleeves 10 are permanently
attached to the top plate 9 to form a sleeve assembly 8 which may
be removed as one unit when the top plate fastenings are released.
In the sleeve assembly 8, the sleeves 10 are supported at the lower
end by a guide member 11 which maintains the spacing amongst the
sleeves 10 and also between the housing 2 and the sleeves 10. The
sleeve assembly may be removed either with the magnet rods 12
within the sleeves 9 or after removal of the magnet rods.
In a modified embodiment (not shown in the figures) the magnet rods
comprise a number, e.g. five, individual magnets which may be
spaced longitudinally e.g. using spacers made of some non-magnetic
material such as a plastics material. The individual magnets could
be loose and installed simply by sliding into the sleeves,
alternating with spacer elements. Alternatively, the magnets and
spacer elements could be part of a magnet assembly which retains
the magnets and spacers relative to each other, allowing simpler
insertion of the magnets into a sleeve. The reasons for this are
explained below
Alternatively, the permanent magnet rods 12 could be replaced by
electromagnets 12. See FIG. 3. The electromagnet rods 13 are in
most respects the same as the permanent magnet rods 12 except that
a soft iron core (or similar), winding and electrical supply is
required. In a modification, each rod could be made up from a
number of electromagnets spaced apart by non-magnetic material, as
described above.
In FIG. 4A, which is a sectional view, the sleeve assembly 10 can
be seen in place within the filter housing 2. One magnet rod 12 is
shown being inserted into its sleeve. Upper and lower guide members
11 are shown. FIG. 4B shows a plan sectional view showing the
magnet rods 12 in place in the sleeves 10 and also showing the
guide members 11 which space the sleeves from each other and from
the housing 2.
FIGS. 5A and 5B show a second embodiment which is the same as that
described above except that gas inlets 14 are provided in the lower
end cap 15. The second embodiment is shown with permanent magnet
rods 12, but the alternative magnet types and configurations
described above apply equally to this embodiment.
In a modification of either embodiment, the magnetic filter unit 1
may be oriented such that the axis of the cylindrical housing 2 is
horizontal or at some angle between vertical and horizontal. Gas
inlets can be provided along vessel's lower surface. The reasons
for this are explained below.
An individual filter can be sized for fluid flowrates typically
ranging from 10 to 200 m.sup.3/h. Since the units are modular,
multiple units can be provided in parallel to provide on-line spare
capacity or to achieve higher flowrates. The magnets generally
range in diameter from 2 cm to 10 cm although larger diameter
magnets can be used, especially when electromagnets are used. The
neodymium magnets are typically provided with a non-corrosive
coating containing any of a variety of materials including nickel,
copper, zinc, epoxy or rubber. The sleeve into which the magnets
are inserted would generally be between 30 cm and 200 cm in length
and typically 2-6 mm larger in diameter than the outside diameter
of the magnets. For applications with permanent magnets, a series
of smaller length magnets would be used held together end-to-end by
their own magnetic attraction forces. The selection of the magnet
material must consider the temperature of the process fluid,
generally from 1.degree. C. up to 200.degree. C. for
neodymium/iron/boron magnet alloys. For temperature applications up
to 860.degree. C., other magnetic alloys must be used. The vessel
& sleeve material of construction should be non-magnetic,
corrosion resistant and suitable for the operating temperatures
expected. One example material would be reinforced polyester resin,
also called fiberglass reinforced plastic.
Example 1
Returning to the first embodiment shown in FIGS. 1 to 4, the
magnetic filter unit 1 is connected into a closed loop cooling
water system in a natural gas liquefaction plant (not shown in the
drawings). The filter unit 1 is oriented horizontally, i.e. with
the axis of the cylinder horizontal. The end cap 15, which is shown
at the bottom of the filter unit 1 in FIG. 1A, is to one side in
this arrangement, and the top plate 9 at the other side of the unit
is oriented vertically.
In a further modified embodiment, when the unit is oriented
horizontally, the end cap 15 could be replaced by a second
tubesheet. The magnet sleeves can then run the full length of the
housing and be supported at each end. Magnets may be inserted or
removed at either or both ends of the sleeves. If desired, each
magnet element can be only half the length of a sleeve and each
sleeve can hold two magnets which are inserted and removed at
respective ends of the sleeve. In this event the feed inlet 3 and
drain 6 would be provided in the side wall of the housing 2.
Because it is a closed loop and ferromagnetic solid production
rates are low, the filter is installed such that only a small
portion, typically 0.5-10% of the total flow is processed. This
also significantly reduces cost. A sidestream of the contaminated
cooling water supply is connected to the filter unit via the feed
inlet 3 in the end cap 15 and product outlet 4 is connected back
into the cooling water circuit, so that cleaned cooling water is
returned to the circuit. The backwash inlet 5 is connected to a
source of clean fresh water and the drain outlet 6 to a suitable
location for disposal.
Contaminated cooling water flows through the filter unit and
ferromagnetic material is deposited on the sleeves 10. All or most
of the ferromagnetic material in the cooling water stream is
removed so that clean water flows from the product outlet 4. The
ferromagnetic material is a mixture of metallic iron particles,
iron compounds such as oxides and also organic compounds which may
have reacted with iron or iron oxides from the pipework.
In practice, the cooling water flow will vary significantly with
the application. In petrochemical applications, an example flow
would be 10,000 m.sup.3/h. A design that targets filtering 5% of
the flow would need to process 500 m.sup.3/hr and would require 3
or 4 vessels, each about 1 m in diameter, 1 m long with 0.2 m
diameter inlet and outlet connections, very reasonable for this
application and the expected solids loadings. The residence time of
the water in the filter would be 10 to 15 seconds. Particle removal
efficiency would depend on site conditions including particle size,
temperature, and the strength of the magnets used.
Some of the iron compounds are soluble. A chemical additive, e.g.
hydrogen peroxide, is introduced to the cooling water stream and
the stream heated; this results in solid ferromagnetic particles
precipitating out of solution. This process is carried out
immediately upstream of the filter unit 1 and the ferromagnetic
precipitate is then captured by the filter 1. At this stage the
inventors have not explored in detail the chemistry of causing
soluble iron compounds to form ferromagnetic precipitates, but they
believe that it may be possible to achieve this effect without
heating.
Once the filter has been running for typically 10-180 days, it is
desirable to clean accumulated magnetic material from the sleeves
10 in the filter unit 1. The valves on the feed inlet 3 and the
product outlet 4 are shut and the filter is isolated from service.
The filter can be either bypassed or the sidestream flow can be
directed through a parallel circuit to another filter. The magnet
rods 12 are then manually removed from the sleeves 10 using the
handles 7. When the magnets are small and lightweight, a horizontal
orientation of the filter unit 1 makes this operation more
straightforward than if the unit had been arranged vertically. In
modified embodiments, the removal of the rods 12 could be automated
or a mechanical aid can be provided to assist with carrying the
weight of the magnets. In the alternative embodiment with
electromagnets, the magnets may simply be switched off to remove
the magnetic field. However, even if electromagnets are used, it
may still be desirable to remove the magnets completely in case of
residual magnetism in the electromagnets.
The valves 5 and 6 are then opened and fresh water is passed
through the unit to remove accumulated magnetic material, which may
be freed from the sleeves because it is no longer subject to a
magnetic field. Surfactants or other chemicals can be added to the
flush water to aid in the removal of the accumulated ferromagnetic
materials.
In a modified embodiment, the influent flow of liquid during
flushing is temporarily suspended and gas (e.g. nitrogen) is
bubbled or sparged through the gas inlets 14. The gas bubbles will
serve to create turbulence and thereby aid in the removal the
accumulated ferromagnetic material from the sleeves (see FIG. 5).
Nitrogen is the preferred gas for sparging because if its
inert-ness and relatively low cost.
Sparging may have the effect of reducing the amount of flush water
required, thus saving water. Depending on the number of filter
vessels in parallel in an installation and the amount of
accumulated material, it may be practical to reuse the spent
flushing water from one filter unit in the cleaning of successive
units.
Example 2
In this example, all details are the same except that the filter
feed 3 is connected to a flow of hydrocarbon liquid, e.g. crude
oil, liquefied natural gas or some other fraction of crude oil and
the product outlet 4 is connected back into the same process flow.
In this example, the liquid used for flushing may be the feed, an
organic solvent or a detergent solution in place of fresh
water.
In either example, periodic maintenance of the magnetic rods may be
required and this is easily done by removing one or more rods at a
time whilst continuing to operate the filter with the remaining
rods in place, or alternatively substituting replacement rods
whilst the original rods are serviced.
In closing, it should be noted that the discussion of any reference
is not an admission that it is prior art to the present invention,
especially any reference that may have a publication date after the
priority date of this application. At the same time, each and every
claim below is hereby incorporated into this detailed description
or specification as a additional embodiments of the present
invention.
Although the systems and processes described herein have been
described in detail, it should be understood that various changes,
substitutions, and alterations can be made without departing from
the spirit and scope of the invention as defined by the following
claims. Those skilled in the art may be able to study the preferred
embodiments and identify other ways to practice the invention that
are not exactly as described herein. It is the intent of the
inventors that variations and equivalents of the invention are
within the scope of the claims while the description, abstract and
drawings are not to be used to limit the scope of the invention.
The invention is specifically intended to be as broad as the claims
below and their equivalents.
REFERENCES
All of the references cited herein are expressly incorporated by
reference. The discussion of any reference is not an admission that
it is prior art to the present invention, especially any reference
that may have a publication data after the priority date of this
application. Incorporated references are listed again here for
convenience: 1. U.S. Pat. No. 8,900,449 2. GB762,163.
* * * * *